This invention relates to apparatus and processes for removably attaching an accessory mounting adapter to a main structure. More particularly, the present invention relates to a mounting arrangement for retaining an accessory adapter on a vehicle so that the adapter is capable of accepting substantial loads when attached. The present invention is particularly useful as a universal accessory attachment to motor vehicles such as trucks, automobiles, vans, campers and the like wherein the adapter for attaching the accessories can be easily removed leaving the mounting framework so as not to interfere with the normal functions of the vehicle structure.
Various devices have been developed in the past for the purpose of permitting temporary attachment of accessories to motor vehicles and the like. Link and pin arrangements have been used where the attachment is for a separately wheeled vehicle as for obsolete railway car connections, farm vehicles and the like. Such loose attachment configurations are not suited for supporting the weight of the accessory and thus there have been some efforts to develop improvements along these lines. For instance, the Graybill et al U.S. Pat. No. 2,867,402 shows an arrangement for attaching a framework to the bumper of a motor vehicle. Such attachments are useful for relatively light loading purposes but the general structural weakness of vehicle bumpers frequently precludes their use for substantial loads. Accordingly, other devices have been developed for the purpose of transferring the load to the substantial vehicle frame members such as the outboard motor carrier shown in McCharen U.S. Pat. No. 2,592,050. Various other arrangements have been developed for attaching accessories to the vehicle frames particularly for trailer hitches and the like. Such devices require relatively permanent attachment to the vehicle frame and cannot be easily removed when not needed.
Accordingly, there have been further efforts to provide a removable carrier attachment for motor vehicles. For instance, U.S. Pat. No. 3,039,634 by Hobson et al suggests an arrangement for clamping tubular members to the underframe of an automobile and pinning an outboard motor carrier to the tubular members when it is needed. Yet another arrangement suggested for attaching a carrier for a motorbike or the like to a vehicle frame is shown by U.S. Pat. No. 3,796,333 by Goldstein wherein the trailer hitch of an existing mount is replaced by a pivotal bicycle or motorbike carrier structure.
The arrangements which permit detachment of the accessory from the vehicle with relative ease either require the continued extension of mounting members beyond the vehicle contours such as the trailer hitch of the Goldstein patent or apparatus which reduces the road clearance for the vehicle as with Hobson et al. Further, the list of items which it is desirable to attach to a vehicle from time to time challenges the imagination. For instance, special attachments have been provided for ball hitches, winches, towbars, snowplows, push bumpers, hoists, bike or motorcycle carriers, camping accessory carriers of all sorts, sports equipment carriers such as ski racks and so forth. Thus there has been a continuing need for an adapter attachment for a motor vehicle which can be easily changed so as to accommodate one or more of various accessories or accessory functions but can be removed in such a manner as to not impair the normal function of the vehicle body, the bumper in particular. The mounting arrangement for this adapter for many applications must be secured to the vehicle underframe with sufficient rigidity to accept substantial loads as in the case of towbars, ball hitches, winches and the like. Even further, the mounting framework for receiving the accessory adapter must be capable of accommodating a considerable variance in spacing as to major structural underframe members.